DESCRIPTION (Investigator's Abstract): The long term goal of this work is to optimize the fetal cell transplant technique so that it can become a viable therapeutic alternative for patients with Parkinson's disease. In this proposal, the PI will transplant embryonic mesencephalon containing dopamine neurons into squirrel monkeys with MPTP-induced parkinsonism. Parkinsonian animals will be treated with steroids for two months, or cyclosporine/ prednisone/azathioprine for two months or six months. Control animals will not be immunosuppressed. Outcome comparisons will be based on behavioral improvement, cell counts of surviving dopamine neurons, and histologic markers of inflammation. The results will provide information which will be valuable for defining the role of immunosuppression in primate neurotransplantation.